HOW TO DO MASONRY OF BLOCK-WORK
HOW TO DO MASONRY OF BLOCK-WORK
INTRODUCTION / SCOPE
This method statement covers the
requirements, equipments and procedures to be used for AAC block work.
REFERENCE
Following documents shall be considered
as reference for execution of the job:
a) Architectural GFC drawings provided by consultant.
b) Site instructions.
c) Checklist for Block work
MATERIAL
AAC Block, Stone dust, PPC Cement, Water, Steel
Bars, Aggregate, Chicken wire mesh.
APPARATUS /
EQUIPMENT
Mixer
machine, Measuring box, Right angle, Grooving tools, Hand saw, Trowel, Plumb, Bucket, Thread, Scraper,
Brick Hammer, Spirit Level or Bubble Tube, Steel Tape, Aluminum fanti ,
HEALTH AND SAFETY
PROVISION
a)
The work place is
to be free from all kind of debris.
b)
Specific safety
measures are to be followed as applicable.
c)
All working
platforms are to be inspected.
d)
Use of Mask
during AAC Blocks cutting.
PREPATORY WORK
a)
Obtain relevant
approved GFC drawings.
b)
Hacking on the
contact area of vertical RCC surface to be done and chicken wire mesh to be
fixed with cement slurry.
c)
Layout should be
done as per the drawings before commencing block work.
d)
Arrange for all
materials such as AAC blocks(600*200*200 & 600*100*200), cement, stone dust
and steel
e)
Cement for next
day early hour work to be issued in advance.
f)
Arrange any
support structure like staging for working at heights.
g)
Empty cement
bags, of 3’ width to be laid before starting of Block work.
WORKMANSHIP- BLOCK
WORK
Strength:
a) AAC Blocks used in block work shall be of approved strength and shall
be true to the shape and dimensions.
b) One Steel bar of 8mm should be used after every 3rd layer in 100 mm
block work.
c) Cement mortar should be 1:6 with the thickness of 10mm with proper
mixing by mixer machine.
Line and Level:
a) Block work should be in proper line, level and plumb.
b) Block work of 100 mm should not be raised more than 1200 mm in one
day.
PROCEDURE OR
METHODOLOGY
a)
Chipping should
be done on all RCC members so as to remove any extra concrete on the surface.
b)
Block surface can be
moistened gently using sprinkler water
c)
Layout should be
done according to the GFC drawing.
d) Chicken wire mesh to be fixed with cement slurry in contact with RCC
surface and AAC blocks. The total gap between RCC and block work should not be
more than 15mm, this thickness includes cement paste, chicken wire mesh and
thickness of mortar.
e)
Proper mortar
shall be prepared for 200mm and 100mm block work, i.e., 1:6 ( 1 cement: 6
sand), (NOTE- Do Not USE RICH MORTAR)
f)
Bottom layer
should be done using a thick layer of 1:6 cement sand mortar to help in leveling.
g)
Corner blocks are
to be laid first.
h) Maintain a
regular pattern of masonry. Blocks are to be laid one over the other with
minimum 1/3rd or 100 mm overlapping (whichever is more)
i)
1 Nos-8mm dia steel bar is to be put after
every 3rd layer in 100mm block work. Steel should be inserted 25mm
in column, using the hammer drill.
j)
Proper use of
plumb and thread is to be made for correct alignment in vertical and horizontal
directions.
a.
k)
Block joints should
be cleaned with the use of fiber blade.
l)
Clean the area
after block work.
m)
Date of construction
should be marked on block work.
n)
Curing should be
done at all joints with sprinkler for 7 to 10 days.
o)
Mullion (A RCC column
size-150mm x thickness of wall of M20 grade of concrete with 4 no’s 10mm dia
steel with 8mm dia ties @150mm c/c imbedded in top beam & bottom slab with
HY150 Hilti chemical) to be provided in all doors & window opening.
p) Diagonal and right angles of the room should be as per requirement.
q) On placing the next block, joints between the two blocks is to be
fully filled with mortar, so that no hollow space is left between the blocks.
r) For electrical conduits and piping installation, cut a chase using an
electrical router or a chasing tool
s) Do not chase block back-to-back for lesser thickness blocks. Chases
depth should be limited to 1/3rd of the thickness of wall
t)
Anchors used with AAC shall be made of
plastic or nylon or polyamide, Wood, fiber, lead, metal or expansion anchors should not be used..
u)
To make the holes for fasteners power
drills are to be used in drilling mode. Usage of hammer mode in drilling is to
be avoided
v) Mortar fallen on the laid empty cement bag, is to be collected &
brought in use at an interval of every one hour.
w) Quantity of mortar prepared should be sufficient enough, such that no
mortar is left after the closing of work.
x) Clean the area after finishing of work.
INSPECTON
a) Chipping has been done.
b) To check layout as per drawing with dimension and diagonal.
c) Mortar mixing of specified ratio and is done through mixer machine
only.
d) 1 number 8 mm dia Steel bar should be used after every 3 layers of
Block in
100mm thick block work.
e) Block should be moist for at least 30 minutes before its use.
f)
Block work is in
line, level and plumb.
g) All the vertical joints in alternate courses should be in the same
vertical line.
h) Area is clean after completion of work.
i)
Block joints to
be maintained 5mm deep.
j)
Date of block
work has been marked.
k) 7 to 10 days curing is being done.
IMPORTANT
PARAMETERS OF AAC BLOCK
S.No
|
Parameter
|
AAC
Blocks
|
1
|
Size
|
600
mm x 200 mm x 100/200 mm
|
2
|
Variation in Size
|
1.5 mm (+/-)
|
3
|
Compressive Strength
|
3-4 N/mm2
|
4
|
Dry Density
|
550 -700 kg/m3
|
5
|
Fire Resistance (8″wall)
|
Up to 4-7 hours.
|
6
|
Cost Benefit
|
Reduction in dead weight leading to savings
in steel and concrete.
|
DO’S AND DON’T’S
IN AAC BLOCK
S.No
|
DO’S
|
DON’T’S
|
1
|
Surface of AAC blocks to be joined with
mortar is to be moist with sprinkler
|
Do not soak AAC blocks in water
|
2
|
Use only compatible mortar 1:6 (1 cement :
6 sand)
|
Do not use rich mortars
|
3
|
AAC masonry should be as per IS code 6041
(1985) and IS code 1905 (1987)
|
The mortar should not be spread much ahead
of the actual laying of blocks.
|
4
|
Chases for services in AAC masonry should
be as per IS code 1905 (1987)
|
Do not deviate from the norms of chase
cutting specified in the code IS 1905 (1987)
|
5
|
Use electro mechanical rotary tool for
chase cutting
|
Do not use chisel and hammer for chase
cutting
|
6
|
Chases should be filled along with
plastering and a layer of chicken mesh is to be embedded in the plaster over
the width of the chase with proper over lap.
|
Do not fill the chase, up to the top
surface of the masonry
|
7
|
Stack blocks in a dry and flat even surface
|
It is important to avoid contact
with water during storage.
|
8
|
If blocks have become wet, it is important
to let them dry properly before usage
|
Do not use wet blocks during
masonry.
|
9
|
Layers can be alternated at every 3-4
layers during stacking
|
Avoid one on one block stacking to prevent
corner chipping
|
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